CN103984849A - Aircraft tire floor print calculation method - Google Patents

Abstract

The invention belongs to the technical field of aviation and particularly relates to an aircraft tire floor print shape and area calculation method. The method is characterized by comprising the following steps: after obtaining the rated sizes (namely the diameter D and width B after expansion of a tire) of an aircraft tire standard storage rack product and the initial inflation pressure P of the tire, determining the compression amount delta of the aircraft tire according to the aircraft load F borne by an aircraft wheel, and furthermore determining the tire print area A, tire print elliptical semimajor axis a and semiminor axis b of the tire. The algorithm is simple and convenient in application; the geometrical and physical significance are clear; the aircraft tire floor print calculation method can be widely popularized and applied to military and civil airport ground service or airport construction design. The aircraft tire floor print calculation method has the beneficial effects that an engineering simple and convenient algorithm with sufficient precision degree, static pressure test is not needed to be performed on tires one by one in a laboratory; the area and geometrical outline dimensions of aircraft tire ground prints of airport outfield and aircraft stationing field without inspection and test equipment can be rapidly given out.

Description

A kind of aero tyre ground trace computing method

Technical field

The invention belongs to aeronautical technology field, be specifically related to shape and the area computation method of aero tyre ground trace.

Background technology

The standard aircraft tyre of military aircraft, aircarrier aircraft equipment, at the ground trace that takes off, lands, parks under carrying compressive state, that runway pavement strength is paved in airport calculating, and the important former accurate input parameter that calculates of tire self life-span, wearing quality, pressure suitability, be also the key characterization parameter of evaluating takeoff and landing quality.Therefore, set up the computing method of aero tyre ground trace, have very important practical significance.

According to the computing method in existing standard, specification and open source literature, the computing method of aero tyre ground trace need to relate to a large amount of experimental test parameters, and the historical experience data of the classical model of accumulation, carry out polynomial approximate matching in conjunction with these with reference to coefficient, and require weight, the configuration of different aircrafts to have certain analogy, referentiability.This method is not suitable for lacking testing laboratory by tire static pressure test condition, and lacks the outfield, airport of inspection, testing apparatus and the operation situation that aircraft is stationed ground.Outfield engineering technical personnel often cannot provide area and the geometric shape size of aero tyre ground trace quickly and accurately, therefore need the general-purpose algorithm that a kind of calculation procedure is easy, parameters relationship is distinct, accurate degree is enough badly.

Summary of the invention

The standard aircraft tyre that the present invention mainly equips towards military aircraft, aircarrier aircraft, in the operation field and the operation present situation that lack test figure and testing apparatus, provide a kind of method: after knowing the norminal size of aircraft tyre standard pallet product (diameter D and width B after being tire inflation) and tire initial inflation process pressure P, the aircraft carrying F that just can share according to wheel, determine aero tyre decrement δ, and then semi-major axis a, the semi-minor axis b of the rat area A of definite tire, rat ellipse.The present invention innovates the formula algorithm providing, and can solve puzzlement outfield engineering technical personnel's tire ground trace computational problem.

Technical scheme of the present invention is: a kind of aero tyre ground trace computing method, it is characterized in that, and comprise the steps:

The first, decrement is calculated: be M at Aircraft Quality, determine decrement δ when tire is carried as F, its computing formula is:

$\mathrm{\δ}=\frac{F}{\mathrm{\ξ}\·\mathrm{\π}\·P\·\sqrt{D\·B}}$

In formula, F is the ground vertical load that tire bears, the kg of unit; P is the initial inflation process pressure of tire, the kg/cm of unit ²(in the time that tire label pressure is MPa, note the conversion between unit, 1MPa=10.2kg/cm ²); D is diameter of tyres, and B is tyre width, and the two unit all uses cm; The unit of the tire decrement result of calculation δ of output is also cm; ξ is for reducing contact coefficient, dimensionless, span: ξ=0.75～0.85;

The second, area calculates: calculate in the time that tire decrement is δ, and the area A of tire ground trace, its computing formula is:

$A=\mathrm{\ξ}\·\mathrm{\π}\·\mathrm{\δ}\·\sqrt{(D-\mathrm{\δ})\·(B-\mathrm{\δ})}$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width, and three unit all uses cm; The result of calculation unit of the area A of output is cm ²; ξ is for reducing contact coefficient, dimensionless, span: ξ=0.75～0.85;

The 3rd, shape is calculated: the shape of tire ground trace is calculated, and is regarded as the ellipse that ratio of semi-minor axis length is λ.When ellipse area is A, its semi-major axis is a, semi-minor axis while being b, exists following relational expression to set up:

$\left\{\begin{array}{c}A=\mathrm{\π}\·a\·d\\ \frac{a}{b}=\mathrm{\λ}\end{array}\right.$

The computing formula that draws semi-major axis a and semi-minor axis b of solution system of equations is above:

$\left\{\begin{array}{c}a=\sqrt{\frac{\mathrm{\λ}\·A}{\mathrm{\π}}}=\sqrt{\mathrm{\λ}\·\mathrm{\ξ}\·\mathrm{\δ}\sqrt{(D\·\mathrm{\δ})\·(B-\mathrm{\δ})}}\\ b=\sqrt{\frac{A}{\mathrm{\λ}\·\mathrm{\π}}}=\sqrt{\frac{\mathrm{\ξ}}{\mathrm{\λ}}\·\mathrm{\δ}\·\sqrt{(D-\mathrm{\δ})\·(B-\mathrm{\δ})}}\end{array}\right.$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width, and three unit all uses cm; The oval semi-major axis a of output and the result of calculation unit of semi-minor axis b are also cm; λ is the ratio of semi-minor axis length of rat ellipse, dimensionless, span: λ=1.5～2.0; ξ is for reducing contact coefficient, dimensionless, span: ξ=0.75～0.85;

Each parameter that in the present invention's (aero tyre ground trace computing method), formula relates to, tire carrying is obtained by dynamometry (or weighing) equipment, tire pressure is obtained by pressure measurement reading, wheel diameter, wheel width state clearly in trimmed size book, and there is the size mark of diameter and width on the sidewall of aircraft tyre.

Advantage of the present invention is:

1) only need four input parameters: diameter of tyres D, tyre width B, tire pressure P, tire carrying F, can calculate all required output parameter results.Apply easyly, physics, geometric meaning are distinct, and applicability is strong;

2) be applicable to lack testing laboratory by tire static pressure test condition, and lack the outfield, airport of inspection, testing apparatus and the operation situation that aircraft is stationed ground.Solve puzzlement outfield engineering technical personnel's tire ground trace computational problem.

Brief description of the drawings

Fig. 1 is the oval trace figure of tire

Fig. 2 is the long and short axis scale schematic diagram of the oval trace of tire

Fig. 3 is the schematic diagram that is related to of tire print and airfield pavement stress

Embodiment

Below by specific embodiment, also the present invention is described in further detail by reference to the accompanying drawings.

The aircraft tyre of the Military Aircraft that certain type quality is M=33000kg, diameter of tyres D=103cm(nominal value), tyre width B=35cm(nominal value) and, charge pressure P=12.5kg/cm ²(measured value), tire carrying F=16600kg(measured value).

1. decrement is calculated:

The decrement of embodiment tire is:

$\mathrm{\δ}=\frac{F}{\mathrm{\ξ}\·\mathrm{\π}\·P\·\sqrt{D\·B}}=\frac{16600}{0.8\×\mathrm{\π}\×12.5\sqrt{103\×35}}=8.8\mathrm{cm}$

In formula, F is the ground vertical load that tire bears, the kg of unit; P is the initial inflation process pressure of tire, the kg/cm of unit ²; D is diameter of tyres, and B is tyre width, and the two unit all uses cm; The unit of the tire decrement result of calculation δ of output is also cm like this; ξ is for reducing contact coefficient, dimensionless, value ξ=0.8;

2. area calculates:

The rat area of embodiment tire is:

$\begin{array}{c}A=\mathrm{\ξ}\·\mathrm{\π}\·\mathrm{\δ}\·\sqrt{(D-\mathrm{\δ})\·(B-\mathrm{\δ})}\\ 0.8\×\mathrm{\π}\×8.8\×\sqrt{(103-8.8)\×(35-8.8)}\\ =1099{\mathrm{cm}}^2\end{array}$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width, and three unit all uses cm; The result of calculation unit of the area A of output is cm like this ²; ξ is for reducing contact coefficient, dimensionless, value ξ=0.8;

3. shape is calculated:

The oval semi-major axis a of rat of embodiment tire is:

$\begin{array}{c}a=\sqrt{\mathrm{\λ}\·\mathrm{\ξ}\·\mathrm{\δ}\·(D-\mathrm{\δ})\·(B-\mathrm{\δ})}\\ \sqrt{1.667\×0.8\×8.8\×\sqrt{(103-8.8)\×(35-8.8)}}\\ =24.1\mathrm{cm}\end{array}$

The oval semi-minor axis b of rat of embodiment tire is:

$\begin{array}{c}b=\sqrt{\frac{\mathrm{\ξ}}{\mathrm{\λ}}\·\mathrm{\δ}\·\sqrt{D-\mathrm{\δ}\·(B-\mathrm{\δ})}}\\ =\sqrt{\frac{0.8}{1.667}\×8.8\×\sqrt{(103-8.8)\×(35-8.8)}}\\ =14.5\mathrm{cm}\end{array}$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width, and three unit all uses cm; The semi-major axis a of output and the result of calculation unit of semi-minor axis b are also cm; λ is the ratio of semi-minor axis length of rat ellipse, dimensionless, value λ=1.667; ξ is for reducing contact coefficient, dimensionless, span: ξ=0.8.

Claims (2)

1. aero tyre ground trace computing method, is characterized in that, comprise the steps:

The first, decrement is calculated: be M at Aircraft Quality, determine decrement δ when tire is carried as F, its computing formula is:

$\mathrm{\δ}=\frac{F}{\mathrm{\ξ}\·\mathrm{\π}\·P\·\sqrt{D\·B}}$

In formula, F is the ground vertical load that tire bears; P is the initial inflation process pressure of tire; D is diameter of tyres, and B is tyre width; ξ is for reducing contact coefficient;

The second, area calculates: calculate in the time that tire decrement is δ, and the area A of tire ground trace, its computing formula is:

$A=\mathrm{\ξ}\·\mathrm{\π}\·\mathrm{\δ}\·\sqrt{(D-\mathrm{\δ})\·(B-\mathrm{\δ})}$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width; ξ is for reducing contact coefficient;

The 3rd, shape is calculated: the shape of tire ground trace is calculated, and is regarded as the ellipse that ratio of semi-minor axis length is λ.When ellipse area is A, its semi-major axis is a, semi-minor axis while being b, exists following relational expression to set up:

$\left\{\begin{array}{c}A=\mathrm{\π}\·a\·d\\ \frac{a}{b}=\mathrm{\λ}\end{array}\right.$

Solution system of equations above, show that the computing formula of semi-major axis a and semi-minor axis b is:

$\left\{\begin{array}{c}a=\sqrt{\frac{\mathrm{\λ}\·A}{\mathrm{\π}}}=\sqrt{\mathrm{\λ}\·\mathrm{\ξ}\·\mathrm{\δ}\sqrt{(D\·\mathrm{\δ})\·(B-\mathrm{\δ})}}\\ b=\sqrt{\frac{A}{\mathrm{\λ}\·\mathrm{\π}}}=\sqrt{\frac{\mathrm{\ξ}}{\mathrm{\λ}}\·\mathrm{\δ}\·\sqrt{(D-\mathrm{\δ})\·(B-\mathrm{\δ})}}\end{array}\right.$

In formula, δ is tire decrement, and D is diameter of tyres, and B is tyre width; A is oval semi-major axis, and b is oval semi-minor axis, and λ is ratio of semi-minor axis length; ξ is for reducing contact coefficient;

Each parameter that in the present invention's (aero tyre ground trace computing method), formula relates to, tire carrying is obtained by dynamometry (or weighing) equipment, tire pressure is obtained by pressure measurement reading, wheel diameter, wheel width state clearly in trimmed size book, and there is the size mark of diameter and width on the sidewall of aircraft tyre.

2. a kind of aero tyre according to claim 1 ground trace computing method, it is characterized in that: after knowing the norminal size of aircraft tyre standard pallet product (diameter D and width B after being tire inflation) and tire initial inflation process pressure P, the aircraft carrying F that just can share according to wheel, determine aero tyre decrement δ, and then semi-major axis a, the semi-minor axis b of the rat area A of definite tire, rat ellipse.